This application relates to Time Division Multiple Access (MA) systems.
In a typical TDMA system for mobile phone applications, the cellular base station includes radio channel unit that transmit to add receive from a plurality of users. Therefore, each unit will transmit and receive an "air" or "broadcast" frame comprising multiple time slots. h the AT&T Intelliverse.sup.TM system supposing GSM stands, the radio channel unit are divided into a channel control unit and a plurality of transceivers which are coupled together by a transmit-receive (TRX) bus. Each transceiver typically serves eight users, and an add frame includes eight time slots.
In both systems, it may be necessary to verify the frequency for trasmission and reception between the base station and a particular user, also down to the industry as "frequency hopping". Thus, a decision is made by the radio channel unit or channel control unit before each frame is transmitted as to which frequency should be utilized for a particular user. If the frequency vibration is implemented at the radio frequency (RF) stage in the transceivers, fast frequency synthesizers are needed since a time slot in an air flame is typically only 577 microseconds for GSM systems. Use of such synthesizers tends to be expensive.
It would be more economical to implement the frequency changes at the baseband stage of the be station.